The Sonoran Desert comes alive

Transcription

1 Sonoran Desert Conservation JEFFREY P. COHN The Sonoran Desert comes alive with colors in March. In wet years like this one, yellow and orange Mexican poppies, blue lupines, white chicories, pink parry penstemons, and tiny lavender sand bells carpet the land in a floral display that surpasses the imagination. Creosote and brittle bushes display yellow flowers while a few earlyblooming chollas and hedgehog cacti show off their large, bright red ones. Tall, sharply spined saguaros and rounded barrel cacti stand guard over the desert, and cactus-like ocotillos sport dainty red flowers at the tips of long, thin branches that sway in the wind. This is some of the best habitat in the whole desert, states Gene Dahlem, a Bureau of Land Management (BLM) resource advisor. Dahlem speaks as he drives through the Sonoran Desert National Monument, one of 19 new national monuments created by President Bill Clinton and Interior Secretary Bruce Babbitt during their last year in office. Located halfway between Tucson and Phoenix, the national monument protects 486,000 acres of low mountains, desert thorn scrub, and creosote flats. It includes three congressionally designated national wilderness areas and the remnants of a small, long-abandoned copper mine. Creation of the Sonoran Desert National Monument is part of a much bigger effort to protect large sections of the desert and adjacent lands from further development. Growing populations in Tucson, Phoenix, and other cities threaten the desert with urban sprawl, while energy development could crisscross even the most remote areas with transmission lines. In all, two new national monuments and a new national conservation area have been designated in the Tucson area, and other new or expanded Turk s head cactus. Ocotillo flowers blossom. Arizona hedgehog cactus. national, state, and county parks have been proposed. Together, the effort to protect the Sonoran Desert represents one of the most ambitious, ecosystemwide conservation efforts currently under way in the United States. The Sonoran Desert encompasses 120,000 square miles of southern and western Arizona, southeastern California, the Mexican state of Sonora, and most of the Baja Peninsula. In Arizona, the desert runs from west of Nogales on the US Mexican border north to east of Tucson and Phoenix, and then northwest to near Kingman. It is one of four North American deserts. The Chihuahuan Desert covers southwestern Texas, southern New Mexico, a bit of southeastern Arizona, and northeastern Mexico. The Great Basin Desert stretches from western Colorado across most of Utah and Nevada and into southwestern Idaho, southeastern Oregon, and eastern California. The Mojave Desert, the smallest of the four, includes southern Nevada, northwestern Arizona, and eastern California. By comparison with most deserts, the Sonoran is quite lush. Winter and summer rains over much of its area support a rich growth of saguaro, organ pipe, barrel, cholla, and prickly pear cacti; bushes like creosote and ocotillo; and numerous agaves and yuccas. The desert is also characterized by palo verdes, mesquites, ironwoods, and acacias, legume trees that grow in the low valleys and hillsides, especially along washes. Tall mountains near the desert s eastern margins are covered with thick forests of junipers, oaks, pines, and spruces, trees usually found much farther north. All told, the Sonoran Desert has more than 2,000 plant species 300 of which are cacti and more than 550 vertebrate species. 606 BioScience August 2001 / Vol. 51 No. 8

2 Even before new preserves were created or proposed, national, state, and county parks protected large swaths of the Sonoran Desert and adjacent lands in Arizona. The largest is Cabeza Prieta National Wildlife Refuge, which covers 860,000 acres of desert thorn scrub west of Ajo. Further south along the US Mexican border, Organ Pipe Cactus National Monument protects 330,000 acres. South of Tucson, Buenos Aires National Wildlife Refuge features 116,000 acres of semiarid grasslands, marshes, and woodlands. Closer to Tucson, Saguaro National Park is divided into two sections that total some 93,000 acres of saguaro and palo verde forests. Coronado National Forest includes most of the Santa Catalina Mountains to Tucson s north, the Rincons to the east, and the Santa Ritas to the south. Two state parks north of Tucson Catalina along the western slopes of the Santa Catalina Mountains and Picacho Peak add nearly 9,000 acres. And Pima County s Tucson and Tortolita Mountain Parks, plus Colossal Cave Park, protect another 28,000 acres. The combination of exotic natural areas, year-round warm weather, and little rain has helped fuel an influx of people into Arizona that has increased the state s population by 40 percent since Saguaro cactus stands within the Sonoran Desert National Monument along a historic route know by several names: the Juan Bautista de Anza National Historic Trail, the Mormon Batallion Trail, and the Butterfield Overland Stage Route. Photo: Nancy Guerrero, Phoenix office of the Bureau of Land Management. August 2001 / Vol. 51 No. 8 BioScience 607

3 Cactus ferruginous pygmy owl. Photo: Glenn Proudfoot, US Fish and Wildlife Service. Tucson alone has grown from a mere 250 people in 1865 to 486,000 in 2000, up 20 percent in just the last decade. Pima County, which includes Tucson and most of south-central Arizona, now numbers nearly 850,000, a 26-percent increase since New construction to accommodate a growing Tucson consumes an estimated 6,400 acres of Sonoran Desert a year. It was in Tucson s northwest suburbs in 1997 that sprawl met the cactus ferruginous pygmy owl, an endangered subspecies. At two and one-half ounces, the cactus ferruginous pygmy owl is one of the smallest and least common of owls. The owl was once found in wooded riparian areas of the Sonoran Desert from the Gulf of California to central Arizona. It is also found in Texas and northeastern Mexico along the Gulf Coast. The owl s range in Arizona has dwindled as rivers, creeks, and washes dried up because of groundwater pumping and expansion of the built-up city. Only a dozen birds were known to reside in the Tucson area in More recent surveys have found about 70 owls and 13 active nests, most around Tucson and Organ Pipe Cactus National Monument, says Scott Richardson, an Arizona Game and Fish Department urban wildlife specialist. The discovery of cactus ferruginous pygmy owls forced the county to shelve plans for a school, mall, and other buildings that were to be part of a new development northwest of Tucson. It also sparked a renewed interest in conserving the Sonoran Desert and adjacent lands to protect the owl and other species. And it helped to launch a series of surveys that would extend our knowledge of the owl and other species and form the basis for a major conservation planning effort. The owl has been the impetus for everything we re doing here, says Carolyn Campbell, executive director of the Coalition for Sonoran Desert Protection, a Tucson-based environmental group. We had not previously had to deal with an endangered species or to address issues of development, adds Maeveen Behan about the problems raised by the cactus ferruginous pygmy owl. Pima County faced the prospect of lawsuits and having to seek incidental take permits from the US Fish and Wildlife Service (FWS) for every new development. We realized that the only way to get out [from the requirements of the Endangered Species Act] was to commit to protecting the species, says Behan, an assistant to the county administrator who heads the planning effort to conserve the Sonoran Desert. That realization led to Pima County s first attempt to regulate growth in the Sonoran Desert for environmental purposes. Behan and her boss began a series of meetings in 1998 with land-use planners, environmentalists, developers, ranchers, and others that led the county board of supervisors to undertake development of a multispecies habitat conservation plan. We decided not just to mitigate or slow the decline of the owl, but to place biology in front of development, she says. Our goal was the owl s recovery. The process involved the creation of various committees, task forces, and advisory teams; the hiring of contractors to conduct studies and write reports; and the holding of dozens of public meetings across the county. Babbitt, a former Arizona governor, declared the pygmy owl one of his top priorities, while Rep. Jim Kolbe (R-Ariz.) lobbied Congress to appropriate $3 million to fund the planning process. The county has issued more than 100 reports over the past three years, which, stacked one atop another, make a pile more than 3 feet tall. Individual reports deal with priority conservation areas, riparian recovery, vulnerable species, cultural and historic preservation, mountain parks, and ranch conservation. Key to the whole effort, says William Shaw, chairman of the scientific advisory team, was to ensure the scientific credibility of the planning process. He and his eight-member advisory team helped pull relevant information together, generated lists of species to study, identified experts to examine data and write reports, and reviewed their work. If we did a good job, we will have helped preserve all species in Pima County, adds Shaw, professor and chairman of the University of Arizona s wildlife and fisheries sciences department. We want to incorporate science and conservation into local land-use planning. For starters, the scientists identified 56 plants and animals that were endangered, threatened, or vulnerable in Pima County even if they were still plentiful elsewhere. The list featured the cactus ferruginous pygmy owl as well as the burrowing owl, southwestern willow flycatcher, Swainson s hawk, Merriam s mouse, Arizona shrew, the lowland and Chiricahua leopard frogs, desert pupfish, and seven species of bats. Plants included the pima pineapple, Nichol s Turk s head, and acuna, all barrel-like cacti. Even a pseudoscorpion was included. Next, the county hired experts who identified areas where each of the 56 vulnerable species were found or where suitable habitat existed. The experts generated a series of maps that delineated areas of no, low, medium, and high potential habitat for each. When laid one on top of each other, the maps yielded 2.1 million acres of land in Pima County where preservation would aid one or more of the species. The scientists further divided the area into core zones where biodiversity conservation should be the primary focus, other areas that would be of value 608 BioScience August 2001 / Vol. 51 No. 8

4 for conservation, and still others that could serve as links or corridors to other protected areas or to areas that could be restored to provide habitat. The 2.1 million acres would not be one large park or refuge, Shaw says. Rather, the county s proposed plan will present alternative conservation strategies for local officials and the public to consider. Each strategy sets out different amounts of land to be protected and requirements that developers and others who want to use the land will have to meet. Following another series of public meetings, an 80-member steering committee will make recommendations to the county board. Behan hopes county officials can select a preferred alternative and adopt a funding scheme for the multispecies habitat conservation plan by next summer, with FWS approval by the end of Whatever alternative is adopted, Behan and Shaw say, new and expanded parks and preserves are likely. Although which existing parks and how much land would be preserved is still unknown, some possibilities have already been identified. One is Tortolita Mountain Park, a county park north of Tucson, which could grow from its current 3,400 acres to 37,700. Two others are Colossal Cave, which could jump from 2,500 acres to 21,000, and Cienega Creek Natural Preserve, southeast of Tucson, which might increase from 4,000 to 36,000 acres. Similarly, several new parks might be created. These include a 10,700-acre park in the foothills of the Santa Rita Mountains southeast of Tucson and a 12,000- acre conservation area in the Cerro Colorado Mountains southwest of the city. Both would protect existing ranches. New tax incentives would also be adopted to help keep the 1.4-million acres of privately owned ranches in Pima County which are largely open space operating as ranches rather than being sold for development. To date, most Tucsonians seem to support the plan. We can t continue to grow willy-nilly without creating problems, says Mac Donaldson, a partner in the 72,000-acre Empire-Cienega Ranch southeast of Tucson. We can make the plan work for ranchers. If we fight it, Chiricahua leopard frog. Photo: Jim Rorabaugh, US Fish and Wildlife Service Cactus ferruginous pygmy owl. Photo: Glenn Proudfoot, US Fish and Wildlife Service. we ll lose because the population centers outnumber us. We can use the plan to continue our ability to ranch and to have our children and grandchildren ranch. But not all agree. We don t know what the cost will be or what opportunities we will lose, says Alan Lurie, executive vice president of the Southern Arizona Home Builders Association, of the proposals to create new parks and put restrictions on development. Lurie cites recently adopted Pima County ordinances that require developers to leave natural 80 percent of land they build on in sensitive areas. That s pretty far-reaching, Lurie says, adding that he and other developers still hope the conservation planning process will be good for all players. Meanwhile, early in the planning process, scientists from the Arizona Sonora Desert Museum in Tucson recommended that the county protect an area of Sonoran Desert in the Silverbell, Waterman, and Sawtooth Mountains northwest of the city. The area, known for its plentiful ironwood trees, contains very good habitat for cactus ferruginous pygmy owls, says Tony Herrell, a field manager for the Bureau of Land Management. Ironwoods are slow-growing, long-lived trees with extremely hard wood. At up to 35 feet, they are easily the tallest trees in the desert. Ironwoods provide shade and protection for young saguaros and other desert plants. Their presence can increase the number of bird species in an area by nearly two-thirds. Instead of creating a county park, though, local officials asked the federal government to act instead. Babbitt agreed and, after several public meetings, Clinton created the 129,000-acre Ironwood Forest National Monument in June Before the land can be fully protected, however, BLM officials will have to address several issues. One involves the 650 miles of unpaved roads that crisscross the monument. Used by local residents and hunters, the roads provide access to people who illegally dump trash, engage in target shooting, and hold high school drinking parties. Other issues include grazing rights within the monument and natural gas pipelines and electricity transmission lines through it. We have to decide whether to continue those, Herrell says. A thornier issue involves 56,000 acres of state trust lands now surrounded by the national monument. Trust lands were deeded to Arizona when it became a state to generate money for education and other public programs. Most state trust lands are leased for cattle grazing and mining, but others have been sold for development. Arizona objected to the creation of the national monument because it would limit the state s ability to generate income from the lands. So far, Arizona has declined to commit or sell August 2001 / Vol. 51 No. 8 BioScience 609

5 any of its state trust lands for Sonoran Desert conservation. More immediately (in March), Gail Norton, President George W. Bush s new interior secretary, asked more than 400 congressional, state, local, and tribal leaders from areas around the 19 new national monuments how those places should be protected and used. In reply, a copper mining company suggested that a 900-acre section be withdrawn from Ironwood Forest National Monument. Although the company offered a 400- acre site in return, the 900-acre site includes areas used by the last bighorn sheep herd near Tucson. Elsewhere, following five years of planning, debate, and public meetings, Congress created the 42,000-acre Las Cienegas (Spanish for wetland ) National Conservation Area southeast of Tucson in The conservation area lies in the Sonoita Plains, an arid grassland in southeastern Arizona that acts as a transition zone between the Sonoran Desert to the west and the Chihuahuan Desert to the east. It features a pronghorn herd that numbers about 100 and Cienega Creek, a north-flowing stream that, unlike most desert waterways, has water year round. Cattails, rushes, and sedges grow in the creek s shallows while cottonwoods and willows line the banks. As with the new national monuments, the law creating Las Cienegas restricts new mining claims, limits vehicles to designated roads, forbids new development, and directs BLM to conserve and protect its natural and cultural resources. The agency has laid out alternate conservation strategies for managing existing cattle grazing, restoring native species such as the endangered Gila topminnow, and enabling hiking and other public uses. A decision is expected by spring 2002, says Karen Simms, a BLM team leader who heads the planning for Las Cienegas. Further west, some Tucson conservationists hope to create a new national park in the Sonoran Desert. The new park would include Cabeza Prieta National Wildlife Refuge, Organ Pipe Cactus National Monument, and the 1.6- million-acre Barry M. Goldwater Range, an Air Force and Marine Corps bombing range. People like parks and they take care of parks, says Bill Broyles, a former high school teacher who is leading the effort to promote a Sonoran Desert national park. Refuges are nice places, but if you really want to manage a place properly, you make it a park. Broyles argues that the split management of the Sonoran Desert between the National Park Service (NPS), US Fish and Wildlife Service, Bureau of Land Management, and Department of Defense creates mismanagement that can be fixed only by concentrating authority in one agency. Not so, says Donald Tiller, refuge manager at Cabeza Prieta. The park service has a mission and we have a mission, Tiller says of NPS and FWS. Giving NPS authority over Cabeza Prieta could mean paved roads, campgrounds, and other facilities where none now exists, Tiller adds. They put recreation first and we put wildlife first, he says. However that argument is resolved, a number of Tucson groups have urged government and private landowners to adopt plans to rewild the 70,000- square-mile sky islands area of southern and eastern Arizona, western New Mexico, and northern Mexico. The area is where the Rocky and Sierra Madre Mountains as well as the Sonoran and Chihuahuan Deserts meet. It harbors more than half of North American bird species and about 3,000 plants, says Roseann Hanson, executive director of the Sky Island Alliance. Acuna cactus. Photo: Jim Rorabaugh, US Fish and Wildlife Service In a report released last year, the environmentalists recommended using existing or proposed new preserves and conservation easements to establish links between currently separate parks and other protected lands. The proposed Cerro Colorado conservation area, for example, would provide a corridor between Buenos Aires National Wildlife Refuge and the Santa Rita Mountain division of Coronado National Forest. The proposed Santa Rita park would connect with the Empire-Cienega Ranch and with Las Cienegas National Conservation Area. Las Cienegas would, if new areas are added to the north as originally intended in the legislation creating the conservation area, link to Pima County s Colossal Cave Park. And Colossal Cave, in turn, would connect with the eastern division of Saguaro National Park, and through it to the Rincon division of Coronado National Forest to the east. We are not talking about creating a new refuge or national park, nor are we talking about taking over private lands, Hanson says. We are talking about creating healthy, balanced wildlands that would include parks and monuments and private lands that are still largely undeveloped. As a first step, the Sky Island Alliance surveyed US Forest Service (USFS) land in Coronado National Forest. The group found numerous illegal roads built by hunters and loggers that USFS officials did not know existed. Sky Island Alliance volunteers have already helped USFS eliminate 30 miles of illegal roads. This is an arid, fragile environment that requires a lot of land to protect the ecosystem, says Luther Propst, executive director of the Sonoran Institute, a Tucson-based group that helped get Las Cienegas declared a national conservation area. Propst was speaking of the Sonoran Desert and adjacent lands. All of the most important and best areas are already developed, he adds. We have to conserve what is left. Jeffrey P. Cohn is a freelance writer living in the Washington metropolitan area. 610 BioScience August 2001 / Vol. 51 No. 8